Papers by Keyword: Error Separation

Abstract: ion Method for Displacement Response in the Sweep-Frequency Testing of Rotating Spindle Guo Yuzhu^{1, a*}, Chen Tianning^{1, b}, Wang Xiaopeng^{1, c} and Xu Yanfei^{1 1} State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, 710049 Xi’an, China ^aguoyuzhu@126.com, ^btnchen@mail.xjtu.edu.cn, ^cxpwang@mail.xjtu.edu.cn Keywords: Rotating spindle; Sweep-frequency measurement; Error separation. Abstract. In the measurement of motorized spindle dynamic performance, the non-contact sweep-frequency excitation is adopted to obtain the displacement response of spindle rotor under high speed rotating. Due to the shape error at measurement section, eccentric error and random vibration, the illusory signals is introduced to the practical measured signal, which makes it difficult to analyze the displacement response. To effectively separate the error, a new method combining template signal and slip filtering is presented. After analyzing the characteristics of displacement response and illusory signals in time-frequency domain, the template signal constructed by the non-superposing portions between response and error is employed to eliminate the error in superposing portions. And a band-pass filter which can slip in time-frequency domain is employed to eliminate the other error. A spindle of CNC milling machine is tested at 7000 r/min, and the analysis result shows that the displacement response can be abstracted successfully from the original signal measured by rotating spindle.

Abstract: A dual probe non-contact ball roundness measurement method is presented in this paper. With two probes aligned in opposite directions, the direct measurement of diameter variation can be obtained. The relationships between diameter variation and out of roundness of a precision ball are discussed. Attempts of error separation using multiple measurements are carried out and the eccentricity of ball and spindle axis is measured. Measurement results indicated that other than the spindle radial run out, which is synchronous in nature, there also exists high frequency non-synchronous variations. Such non-synchronous errors can be effectively eliminated with the dual probe arrangement for diameter variation measurement. The measurement results showed that such set up is capable of measuring high precision balls for diameter variation and out of roundness with uncertainty of less than 10nm. Single measurement can be completed in 10 seconds with over 10,000 data points. Faster measurement is possible with improved air bearing spindle. The method is suitable for online application of precision ball diameter variation and out of roundness measurement.

Abstract: Two-point method designed of the test system for application, the precision of the motorized spindle rotation was dynamic measurements. The system consists of standard bars, high-precision non-contact eddy current sensor. Analyzed by a mathematical model to establish error separation, measurement of two spindle rotation accuracy. The use of two isolated error method for processing the experimental data obtained spindle rotation accuracy at different speeds. Studies have shown that when the spindle speed of 10,000 rpm rotational error is small and tends to be more stable. Identify the factors that affect the accuracy of spindle rotation and summarized. Spindle rotation accuracy on-line monitoring and speed control provides an important theoretical, experimental basis.

Abstract: To improve the measurement accuracy of two-dimensional (2D) precision working stages in the semiconductor manufacturing industry, an error separation and dynamic compensation method based on a planar grating is proposed for a 2D coplanar displacement measurement system. In the system, a planar grating of HEIDENHAIN PP281R is fixed in the center of precision working stage to build coplanar structure and reduce Abbe errors. And the system errors including grating period carved error, temperature effect, vibration effect and mount effect are modeled, calculated and separated. Then the separated errors are dynamically compensated from the corresponding displacement measurement results through data-processing software. Analysis results show that the proposed error separation and dynamic compensation method based on planar grating can improve the measurement accuracy of the coplanar displacement measurement system effectively.

Abstract: Aiming at the low efficiency and precision of nowadays domestic auto-straightening machine of shafts, a new kind of shafts straightness detection system is researched and developed. The supporting part of the measuring mechanism adopts the mechanical structure of auto-going-down of straightening points supporting pedestal. The whole convolute measuring system fixes on the machine tool orbit sliding table, whose movement can change the position for the straightening point and make positioning faster and more accurate. In addition, this detection system bases on applications math and builds math model by Fourier transform which can separate the elliptical error signal, straightness error signal and impulse error signal and then gained ideal straightness error of shafts.

Abstract: According to the error character of the systematic error and random error in calibration data, we put forward using wavelet analysis method to the process of separating error. We give the basic principle and method to dispose random error with Wavelet Analysis. When choosing the threshold, we use GCV(Generalized Cross Validation) principle. Then use IA to search the best value of GCV function and realize the separation simulation of random error in the MATLAB. During the selection operation of IA(Immune Algorithm), the expecting propagation probability is computed in order to guarantee the diversity of the colony and the robustness of algorithm. The results of simulation show that the combination of Wavelet Transform and IA can achieve the aim of separation and have some application prospect in this field.

Abstract: A new three-point method for spindle roundness error measuring was introduced, three capacitive sensors were installed on the measured shaft circularly, and with a certain angle each other, while the spindle was rotating with a certain speed, the capacitive sensors had measurement on the circular profile simultaneously, then through linear combination for three-sensor output signals, the roundness error was effectively separated from the spindle error. There were no strict requirement to initial installation position by using capacitive sensors, as long as ensuring the change of measured rotor error within the linear range of sensors, we could realize effective measurement. The experiment results have verified the effectiveness of roundness error measuring system based on three capacitive sensors.

Abstract: The measurement error contains many errors in NC machine tools processing and those errors will be mapped to workpiece at certain regularity. The control of error caused by cutting parameters during the precision and ultra precision process is one of the key technologies in NC machine tools processing. This article introduces Bayesian networks into the dynamic error separation modeling, with the learning process of Bayesian network structure and establishes the error separation model based on Bayesian networks, then carries out the comparison and analysis between simulate and experimental data to verify the feasibility of the method.

Abstract: On the foundation of conventional double-flank gear rolling tester, a virtual detector of gear error taking personal computer as the core is developed with the use of virtual instrument technology. Systematic error is analyzed through error separation technique. The structure of the detecting system , the design of the system software based on LabVIEW, and the separation of different radial component deviations of gear are presented.

Abstract: In this paper, a synthesis modeling method of geometric and thermal error is presented. Through the analysis of machine error data at varying temperatures, the error distribution rule is obtained. Based on the different characteristics of geometric error and thermal error, error separation method has been carried out in the modeling. Using polynomial fitting for geometric error and linear fitting for thermal error, a synthesis mathematical model has been proposed. This error compensation method concerns the variations of geometric errors at different temperatures in the machine working, thus a comprehensive analysis is made on the error and its regularity from the overall temperature rise to the heat steady-state. Both at low and high temperatures in the machine working, the experimental validations show that the positioning errors of the machine tool are reduced effectively after applying the error compensation approach.